No power and popping through intake when cold


2001 KIA Sportage.

Has new fuel injectors, PCV valve, Fuel pump, air filter, spark plugs.

Car onlly acts up first thing in the morning when cold for about 5 minutes. After that runs great!

Checked ECT OK.

Checked Mass Air Flow sensor OK.

EGR is not stuck open.

I am lost!

Any advice?

Could it be carbon build up on intake valves causing this?




It almost has to be a valve seating issue. It is strange that it goes away when warm. Warped valve?, maybe. Is the popping definitely a combustion leak?


Sounds like a sticking intake valve due to a buildup of varnish or crud on the valve stem. This can be caused by too many short trips, using poor grades of oil, or stretching the oil change intervals too far.

There are oil additives that claim to clear up sticking valves, although I’ve never used them so can’t recommend a specific product.


it could be a sticking lifter and when the oil get hot and thiner and pressure get build up it moves the valve. try oil cleaner . you could take a compresion test when the engine is cold this is not hard to . if you have no perssure in one cylinder oyu found the wright cyl. carbon build up could keep a valve frm closing all the way but the carbon will be there even when the engine is hot . check the timing see if it changing if timing is not correct it will want to fire in the wrong order.